1) Field of the Invention
This invention relates generally to surface mount assembly of semiconductor devices and more particularly to a method and device for converting a pick and place handler for use with devices having different packages and/or different sizes.
2) Description of the Prior Art
Pick and place handlers are widely used in surface mount technology for physically moving semiconductor devices during assembly and test. A vacuum lead is typically used to pick up a semiconductor device and hold it during transport to a new location (e.g. a circuit board or a holding fixture). However, different packages and even different sizes of a common package can require different vacuum leads.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following patents.
U.S. Pat. No. 5,184,068 (Twigg et al.) describes a pick and place handler.
U.S. Pat. No. 5,966,940 (Gower et al.) shows a thermal conditioning unit that can be incorporated into a pick and place handler.
It is an object of the present invention to provide a method and device for converting a pick and place handler to accommodate various semiconductor packages and/or sizes.
It is another object of the present invention to provide an economical method and device for converting a pick and place handler to accommodate various semiconductor packages and/or sizes.
It is yet another object of the present invention to provide a method for converting a pick and place handler to accommodate various semiconductor packages and/or sizes with reduced conversion and set-up time.
To accomplish the above objectives, the present invention provides a method and conversion kit which can be used to convert a pick and place handler for a different semiconductor package economically, and with minimum conversion and set-up time. An input arm assembly is provided with interchangeable vacuum leads such that package-to-package conversion only requires replacing the vacuum lead with a different size vacuum lead. An input/output shuttle pate is provided comprising a block and base plate. The block has a plurality of pocket groupings and a two or more alignment hole groupings. The base plate has two or more alignment pins. Package-to-package conversion is achieved by changing which alignment hole in each alignment hole grouping is set on the alignment pins, thereby selecting the pocket in each pocket grouping corresponding to the alignment hole used. A soak plate is provided having an array of pocket groupings, wherein each pocket grouping has the same pattern of different size/shape pockets to accommodate different packages. Package-to-package conversion is accomplished by programming an offset to the desired pocket in each pocket grouping a test arm assembly is provided with interchangeable vacuum leads and interchangeable nest pieces such that package-to-package conversion only requires replacing the vacuum lead and nest piece with a different size vacuum lead and nest piece.
The present invention provides considerable improvement over the prior art. Setup time is reduced because the input arm assembly and test arm assembly can be converted by changing the interchangeable vacuum lead and the interchangeable nest piece as required, instead of changing the entire input arm assembly and the entire test arm. Set-up time is also reduced by the soak plate and input/output shuttle plate which can accommodate different packages, eliminating the need to replace them. Tool inventory and maintenance cost is reduced because separate input arm assemblies, test arm assemblies, soak plates, and input/output shuttle plates do not need to be provided and maintained for each package that the pick and place handler is to be used with.
The present invention achieves these benefits in the context of known process technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.